Remote setting for electronic systems in a projectile for chambered ammunition

ABSTRACT

A fuze setting circuit in an artillery or tank shell having a case with a press-fitted head assembly is provided with an electromechanical fuze-wiring link that is completed electrically by mechanical assembly of a tracer-carrying projectile on the shell casing, and by the rotational attachment of a programmable fuze onto the projectile.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a divisional of commonly owned U.S. Utility patentapplication Ser. No. 12/278,832, filed Dec. 17, 2008, entitled: REMOTESETTING FOR ELECTRONIC SYSTEMS IN A PROJECTILE FOR CHAMBERED AMMUNITION,this Utility patent application incorporated by reference herein.

FIELD OF THE INVENTION

This invention relates to the field of medium and large-calibre tank andartillery ammunition and provisions for a capability of remotelyprogramming such ammunition in one of several predefined modesimmediately prior to firing. In particular, it relates to theelectromechanical configuration of the circuitry required whenincorporating a multi-functional electronic fuze or other type oftrigger mechanism into the projectile of a multipurpose, large-calibrehigh-explosive or other pay-load carrying cartridge.

BACKGROUND OF THE INVENTION

It is now customary to provide circuitry that allows the fire controlsystem of a gun to remotely select the fuze operating mode as, forexample, either point detonation, or point detonation delay, or airburst through the use of a timing or turn-counter device, or proximityoperating modes, or any combination thereof, after the ammunition isloaded into the gun and before it is fired.

Although the invention described herein is generally applicable tomedium-calibre and large-calibre tank and artillery guns, the specificapplication cited will be that for the 105 mm tank gun. Further,although the invention is described in respect to setting a fuze, theinvention could also be used to activate a trigger for programming acamera, activating a chemical sensor, turning-on a targetdesignator-illuminator or actuating other similar types of payload.

Currently there are two general types of ammunition carried by tankswith 105 mm guns: (1) those containing armour piercing, fin stabilized,discarding sabot (APFSDS) projectiles: and (2) those containing a highexplosive (HE) fill. The former is a kinetic energy penetrator that iseffective against tanks or other “hard” targets, whereas the latter'sexplosive fill detonates upon impact against such targets as fieldfortifications, light vehicles, light structures, and personnel. Theseparate formats of this current technology reduce flexibility andseverely limit the types of targets that a tank can effectively engagerapidly.

This lack of flexibility also makes tanks vulnerable to attack from, forexample, an infantryman armed with a shoulder-fired rocket-propelledgrenade (RPG) launcher, if they are loaded with APFSDS cartridges. Inthis scenario, the tank commander would want to bring anti-personnelfire to bear as quickly as possible in the form of an air-burstprojectile near the attacker to eliminate the threat to his vehicle.This is not possible with the limited choice of discrete ammunition nowavailable for tanks carrying 105 mm guns. The same situation would applyshould such a tank come under sudden air attack from a helicopter.Without an air burst capability at its disposal, defence against such anattack is compromised, nor can effective offensive action be takenagainst “soft” targets such as helicopters, light aircraft or lightlyprotected personnel.

A solution to this dilemma is to have a third type of 105 mm cartridge,one with a multipurpose capability added to the mix of cartridgescarried in tanks such as the Leopard Main Battle Tank. The projectilefor such a cartridge would contain an explosive charge and amulti-option fuze that is governed by a suitable fire control system(FCS) that instantaneously and remotely selects the required fuzesetting of a chambered round in response to a perceived threat. Optionsfor the fuze would include, for example, point detonation (PD), pointdetonation delay (PDD), proximity airburst, and timed airburst. Changesto the setting of the fuze could be made up to the moment the projectileis fired. Once accepted into the inventory, this multipurposehigh-explosive projectile (MPHE) could, in most instances, replace thecurrent HE rounds, thereby enhancing both the offensive and defensivecapabilities of the tank while maintaining just two natures ofammunition on board.

Since the multi-option fuze in a MPHE projectile is to be remotelyprogrammable by the Fire Control System when the cartridge is chambered,it must be electronic in nature. One way to achieve this is to provide agun chamber with a specific hard-wired electrical circuit connecting theFCS to the electronic fuze. However, the existence of large numbers of105 mm tank guns in the inventories of many armies makes it impracticalto require burdensome modifications to all of them for new, hard wiredcircuitry. Thus, it is imperative that no modifications be made to thetank guns that will fire MPHE cartridges.

There are several ways to effect hard wiring between the FCS and thefuze. These include making the electrical contact between the FCS andthe cartridge through: (1) the side of the projectile; (2) the side ofthe case; (3) the base of the case; (4) the primer via the firing pin;or (5) an insulated sheath containing a conductive layer. If there areto be no modifications to the tank gun, it is most practical to utilizethe existing firing pin as the interface with the chambered cartridge(i.e., through direct contact with the cartridge primer). Under thesecircumstances, both the electrical fuze-setting signal and theelectrical firing impulse enter the cartridge through a commonelectrical contact.

It is, therefore, imperative that the design of the fuze-setting circuitinside the cartridge be capable of carrying the setting signal to thefuze, which can be located in either the base or in the nose of theprojectile, at any time up to the moment of firing without prematurelyigniting the propelling charge. Such premature ignition is normallyavoided by the inclusion of one or more blocking diodes, plus the factthat different signal levels are used for fuze setting and firing.

Technology to achieve this is well known and described abundantly in theprior art going back at least as far as U.S. Pat. No. 3,814,017 (nowexpired).

This prior art also describes a variety of novel solutions for theelectromechanical circuitry to physically achieve the remote programmingof a chambered cartridge prior to firing (e.g., the placement ofconductors, the type of conductors, the contacts between various partsof the circuit). Each of these solutions depends on the physical designof the gun/ammunition system under consideration. Common to allsolutions, however, is the requirement for reliable circuitry from thebase of the case through the length of the case to the projectile, andthen onwards to the nose of the projectile where the multi-option fuzeis usually located. The range of solutions in the prior art isillustrated in the six patents discussed in the following paragraphs.

U.S. Pat. No. 3,814,017 shows a design with a similar intent to that ofthe invention. Specifically, it describes a “method and systemarrangement for determining the type and condition of ammunition whichis ready for firing and can be detonated electrically . . . ”. Thispatent, however, which has now expired, does not give details as to howthe various circuits are physically located inside the cartridge. Itonly shows a wire running from the base of the ignition primer throughthe middle of the propellant charge before directly entering theprojectile through a large undefined aperture, which does not appear toseparate the propellant from the projectile in an airtight manner. Thereis no tracer in the projectile and little detail of the variouselectrical connections is provided beyond the written description thatthey are “plug contacts”. The present invention concentrates on aspecific method, different from and more detailed than that described inU.S. Pat. No. 3,814,017, for installing the circuitry in the cartridge.

U.S. Pat. No. 4,015,531, which has also expired, describes a systemwherein the gun voltage for initiating the primer of a round ofammunition having a fuzed warhead is used to “contemporaneously chargethe power supply capacitor of the warhead”. Although this patent isprimarily directed towards high rate-of-fire cannons in airplanes, thegeneral method for transmitting the signal to the capacitor in theprojectile is similar to that of U.S. Pat. No. 3,814,017 detailed in theprevious paragraph. Again, the present invention concentrates on themethod of constructing the circuitry, which is different from the methoddescribed in U.S. Pat. No. 4,015,531 and resolves problems encounteredin the larger cartridges associated with tank guns.

U.S. Pat. No. 5,078,051 is directed “to an improved electricalcommunication system which facilitates the transmission of pre-launchcommunication from the firing mission computer to update the program ofthe round”, including the projectile control system. Its cartridge issimilar to that in the present invention in that it contains a primerflash tube for ignition of the propelling charge through which aconductor in the form of a wire passes before exiting near the base ofthe projectile and continuing outside the projectile before reenteringit in an undetermined way. This part of the circuit in the presentinvention is entirely contained inside the length of the 105 mmprojectile, after entering it through a different path which is onefeature of the invention.

U.S. Pat. No. 5,097,765 describes a remotely set digital time base fuzein a cartridge case where fuze power, time setting information andcartridge firing are performed sequentially over the same hardwire linethrough the electric primer terminal. In particular, the digital timefuze is adjacent to the base of the projectile.

U.S. Pat. No. 5,147,973 follows on from U.S. Pat. No. 5,097,765referenced above. It, too, describes a multi-functional fuze system withoverall performance objects similar to those described in the presentinvention. In this instance there are two fuzes, one of which isessentially identical to that described in U.S. Pat. No. 5,097,765 whilethe other is an independently powered proximity fuze located in the noseof the projectile.

U.S. Pat. No. 6,526,892 describes a hard-wired, remotely programmablefuze system for tank ammunition, but it necessitates modifications tothe tank gun. The electrical connection with the tank in this design isthrough the base of the cartridge case, but it requires a connecting pinand associated circuitry as new, additional components to the gun (i.e.,existing guns would have to be modified to fire the cartridge of U.S.Pat. No. 6,526,892). In this design, entry of the circuit into theprojectile is at its base, but not through the tracer. Furtherrefinements to this design are found in U.S. Patent ApplicationPublication 2004/0003746 A1 (8 Jan. 2004).

Details of Prior Art Electromechanical Circuits

To establish differentiation of the invention from the prior art, it isfirst necessary to take a closer look at three of the inventionsmentioned in Section I above. FIGS. 1, 2 and 3 show the prior artconfigurations for the remote programming of a nose fuze in a largecalibre shell for firing from, for example, a tank. They correspond,respectively, to patents U.S. Pat. No. 3,814,017, U.S. Pat. No.5,078,051 and U.S. Pat. No. 6,526,892. These patents illustrate threedifferent circuit configurations for transmitting the desired signalsfrom a remote fire control system to a programmable fuze located in thenose of a chambered high explosive ammunition round.

In FIG. 1 (prior art U.S. Pat. No. 3,814,017) chamber I of large calibrebarrel 2 contains shell 3 comprising cartridge case 4 and high explosiveprojectile 5 which contains fuze 6. Fire control system 7 is hard wiredto shell 3 via conductor 8, which is connected to shell 3 throughcontact 9 (in breech block 10) and contact 11 (in electrical ignitionprimer 12). Signals from the fire control system destined for fuze 6 areprevented from entering the circuitry 13, associated with electricalignition primer 12, by directing diodes, thereby bypassing saidcircuitry 13 and going onward to fuze 6 via conductor 14 and aperture 15through the base 16 of projectile 5. The circuit is completed throughthe metal portion of projectile body 5 and the metal cartridge case 4,which are attached at joint 17.

In FIG. 2 (prior art U.S. Pat. No. 5,078,051) large calibre cartridge 20comprises case 21 and fin stabilized high explosive projectile 22contained in discarding sabot 23. Fire control box 24 is hard wired tocartridge 20 via conductor 25 and conductive ignition electrode 26,which is contained in primer housing 27. Transmission line 28 connectsconductive ignition electrode 26 with fuze electronics package 29contained in nose cone 30 of projectile 22. En route to electronicspackage 29, transmission line 28 first passes through the interior ofprimer flash tube 31 before exiting through one of the holes 32 at itsforward end to bypass fins 33 of projectile 22. Transmission line 28next enters projectile 22 in an undefined way at the tapered rear end 34of that portion of projectile 22 that contains explosive charge 35 andthen continues on through said explosive charge 35 until it reacheselectronics package 29 in nose cone 30. Transmission line 28 containsthe necessary conductors to transmit signals from fire control box 24 toelectronics package 29 in a fully self-contained manner (i.e., it doesnot require the case 21 or projectile 22 or discarding sabot 23 to bepart of the circuit). As in prior art U.S. Pat. No. 3,814,017 describedabove, signals destined for electronics package 29 are prevented fromentering circuitry (not shown) located near conductive ignitionelectrode 26 that is reserved for the electrical ignition of primerflash tube 31.

In FIG. 3 (prior art U.S. Pat. No. 6,526,892) large calibre cartridge 49comprises case 48 and projectile 78 accommodating tracer unit 96 andprogrammable projectile fuze 79. The case 48 is made up of two parts,base 77 and combustible jacket 36. Primer flash tube 37 is connectedwith base 77 and has an intricately designed contact plug 38 at itsforward end. Contact plug 38 receives cable 39 after said cable 39passes through primer flash tube 37, having entered cartridge 49 throughannular aperture 40 of base 77. Aperture 40 is sufficiently offset fromthe centre of base 77 so that cable 39 is independent of primerelectrode 41 (i.e., the electrical ignition circuit (not shown) and thecircuit to program fuze 79 are completely different and separate); theground for cable 39 is provided by the container 42 that holds electrode41. Cable 39 is, therefore, effectively wired to fire control system 43,which remotely programs fuze 79. Timing cables 44 and 45 emanate fromcontact plug 38 and pass up the outside of the rearward end ofprojectile 78 so as to avoid tracer unit 96. They enter projectile 78 ataperture 46 and proceed through conduit 47 to programmable fuze 79. Thisdesign was subsequently refined as described in U.S. Patent ApplicationPublication 200410003746 A1 (8 Jan. 2004).

The invention described herein as follows includes features in thedesign of an electromechanical circuit that significantly differentiatesit from the prior art described above. The invention in its general formwill first be described, and then its implementation in terms ofspecific embodiments will be detailed with reference to the drawingsfollowing hereafter. These embodiments are intended to demonstrate theprinciple of the invention, and the manner of its implementation. Theinvention in its broadest and more specific forms will then be furtherdescribed, and defined, in each of the individual claims which concludethis Specification.

SUMMARY OF THE INVENTION

The invention features an electromechanical circuit that transmitselectrical setting signals from the fire control system of, for example,a tank in one application, to a programmable fuze situated in the highexplosive projectile of a fully-chambered cartridge in a medium orlarge-calibre gun. One aspect of the invention is to provide a reliableelectromechanical circuit for the transmission of the setting signalthat is both easier, from a production point of view, and moreeconomical to install in contrast to the transmitting circuits describedby the prior art.

According to various aspects of the invention, the electromechanicalcircuit contains up to five contacts or interfaces, each of whichcontains original features in its design. The first of these, known asthe head assembly contact, contains two diodes: one to ensure that thesetting signal for the fuze does not ignite the propellant in the case;and the other to isolate the fuze from the firing signal. Since the headassembly contains several pieces (electrode, bridge wire, primer ordetonator equivalent, relay charges, metal diode holders, insulators,etc.), the configuration of these parts is pertinent to the ease thatthey can be assembled and the resulting reliability and safety demandedby the separation of the setting signal from the firing signal. To thisend, one novel feature of the head assembly contact eliminates thesoldering of electrical connections from the assembly procedure andreplaces this operation by simple press fitting of the parts together.This also helps preserve the insulating integrity of the press-fittedsurfaces. Another feature involves the placement of the diodes and diodeholders such that the conductors leading to subsequent portions of thecircuit can be readily attached thereto. One aspect of the invention,therefore, is the provision of a simple, reliable, easily manufacturedand readily installed head assembly contact integrally containing aportion of the faze signal-setting circuit including one or more diodeshaving accessible electrical connections to the remainder of thecircuit.

The second and third contacts in the fuze-setting circuit, knownrespectively as the rear tracer contact and the forward tracer contact,are unique in that they utilize the electrically-conductive (usuallymetallic) container of the tracer unit to transmit the setting signal.While reference is made to a tracer unit, the same structure may applyin the case of a baseburner or other rocket motor system. Further, theelectrically-conductive container may be empty. This feature of theinvention has the advantage of simplifying the assembly of theprojectile into the casing, automatically establishing theelectromechanical fuze-setting circuit connection at the base of theprojectile and facilitating its entry into the interior of theprojectile at this position. In both instances a simplified series ofmechanical parts, both conducting and non-conducting and including aspring-loaded connector, that are easy to manufacture and assemble makeup the design. Thus, a further aspect of the invention is the inclusionof the tracer unit, specifically the electrically-conductive tracercontainer, in the electromechanical setting circuit for the fuze.

The forward tracer contact is also characterized by an electricalconnection made through at least one novel high-pressure seal to ensureagainst the possibility of hot propellant gases reaching the explosivecharge in the projectile and causing premature detonation. Such sealsmay be made of anodized aluminum or other suitable insulating materials,which not only provide the necessary strength but also allow electricalcurrent to be transmitted only longitudinally (i.e., not transversely tosurrounding media). These seals (one or more) are so arranged as to formpart of the electromechanical setting-signal circuit. An additionalaspect of the invention, therefore, is the inclusion of high-pressureseals in the electromechanical setting circuit for the fuze.

The fourth contact, located at the nose of the projectile case and knownas the fuze contact, uses a spring-loaded connector to ensure a positiveinterface with the base of the fuze. It is effected by an annular ringof a conducting material on the base of the fuze. With this design, thefuze contact will transmit the setting signal to the fuze regardless ofthe rotational orientation of the fuze when it is assembled into thefuze/booster cavity, normally by screwing. Another aspect of theinvention, therefore, is the formation of the projectile body/fuzeelectrical interface in the electromechanical circuit through the use ofa spring-loaded connector in combination with a 360° conducting ring onthe fuze body itself. This form of electrical connection is not limitedto the environment of a programmable shell, but may be applied whereveran electrical contact must be made in conjunction with a threadedmechanical coupling.

This simplified rear tracer contact provides yet another aspect of theinvention by utilizing the tracer container as an integral part of thefuze setting-signal circuit, thereby permitting a unique “plug-in”method of final cartridge assembly that is safe, cost effective andfully reliable. It is achieved following two preassemblies:

(1) Case preassembly, comprising principally the cartridge case loadedwith propellant, primer flash tube with end closure, head assemblycontact, rear tracer contact with spring loaded connector, and a guidetube/funnel; and

(2) Projectile preassembly, comprising principally the projectile loadedwith high explosive, fuze, fuze contact, and tracer unit withelectrically-conductive tracer container.

The final assembly of the cartridge then consists of simply insertingthe projectile preassembly into the case preassembly with the tracerunit being guided into place by the guide tube/funnel. After the rearend of the tracer container of the projectile preassembly comes intocontact with the spring-loaded electrical connector of the casepreassembly, no further adjustment is necessary. This user-friendly“plug-in” operation provides simultaneous mechanical and electricalcoupling at the case/projectile interface that is fully reliable. Yetanother aspect of the invention, therefore, is the creation of apositive setting-signal circuit electrical connection at the interfaceof the two preassemblies when the rear end of the tracer container, orequivalent, is fitted to the spring-loaded electrical connector in thecase preassembly.

The foregoing summarizes the principal features of the invention andsome of the optional aspects. The invention may be further understood bythe description of the preferred embodiments, in conjunction with thedrawings, which now follow.

SUMMARY OF THE FIGURES

FIG. 1 is a cross-sectional view of a prior art large-calibre highexplosive tank shell capable of programming its nose fuze from a remotefire control system as described in patent U.S. Pat. No. 3,814,017.

FIG. 2 is a cross-sectional view of a prior art large-calibre highexplosive tank shell capable of programming its nose fuze from a remotefire control system as described in patent U.S. Pat. No. 5,078,051.

FIG. 3 is a cross-sectional view of a prior art large calibrehigh-explosive tank shell capable of programming its nose fuze from aremote fire control system as described in patent U.S. Pat. No.6,526,892.

FIG. 4 is cross-sectional side view of a 105 mm high explosive shellillustrating the subject electromechanical circuit connecting the firecontrol system to the programmable fuze.

FIG. 5 is a simplified schematic of the electromechanical circuit ofFIG. 4 showing its relationship to the firing circuit.

FIG. 6A is a cross-sectional side view of the head assembly contact.

FIG. 6B is the same view as in FIG. 6A except that the head assemblycontact has been rotated 90° along its longitudinal axis.

FIG. 6C is an end view of the head assembly contact.

FIG. 6D is the same view as FIG. 6A but with an alternate diodeplacement.

FIG. 6E is the same view as FIG. 6B but with an alternate diodeplacement.

FIG. 6F is an end view of the head assembly contact (alternateplacement).

FIG. 7A is a cross-sectional side view of the rear tracer contact.

FIG. 7B is a cross-sectional side view of the electrically conductiveseat for the rear tracer contact of FIG. 7A.

FIG. 8A is a cross-sectional side view of the forward tracer contactwithin the projectile.

FIG. 8B is an enlarged cross-sectional side view of the insulatedelectrically-conductive high-pressure seal shown in FIG. 8A.

FIG. 8C is a cross-sectional side view of an alternative design of theforward tracer contact of FIG. 8A.

FIG. 9A is a cross-sectional side view of the fuze contact.

FIG. 9B is a 3-dimensional depiction of the fuze contact.

FIG. 9C is an enlarged, partial cross-section of the annular contact inthe base of the fuze.

FIG. 10 is a cross-section of the case preassembly and the projectilepreassembly just prior to final cartridge assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 4 large calibre cartridge 50 comprises: cartridge case 51 withcartridge case base 52; head assembly contact 67; head assembly holder53; primer flash tube 54; propellant 55; driving band 56; projectile 57comprising projectile body 57A, projectile base 58, projectile nose 59and a load exemplified by high explosive 60 fill; tracer unit 61A withelectrically-conductive tracer container 61 containing tracer compound62; and programmable multi-functional electronic fuze (or fuze) 63containing fuze electronic circuit 76 as an example of programmableelectronics. Fire control system 64 is hardwired to firing pin 65, whichis located in the breech (not shown), by conductor 66. Firing pin 65bears directly on electrode 80 (see FIG. 6A) of head assembly contact67. Through intermediaries, insulated electrode 80 is eventuallyconnected to conductor 68, which then runs along the outside of primerflash tube 54 to connect with rear tracer contact 69.

The rear tracer contact 69 connects to electrically-conductive tracercontainer 61 (or base burner container or rocket motor) which, in turn,is connected to forward tracer contact 70 assembly whose forward endpasses through conduit 71 in projectile base 58. The terminal end ofconduit 71 serves as a seat for a high-pressure seal described furtherbelow. Conductor 72 is electrically connected to forward tracer contact70 assembly and runs through high explosive 60 and conduit 73 inprojectile nose 59 to fuze contact 74. Conductor 75 is connected to fuzecontact 74 at one end and to fuze electronic circuit 76 of fuze 63 atits other end.

The subject of this invention is the electromechanical circuit thatallows signals originating from fire control system 64 to be transmittedto electronic circuit 76 of fuze 63 in a fully reliable and safe manner.The elements that make up this circuit are: firing pin 65, head assemblycontact 67, conductor 68, rear tracer contact 69,electrically-conductive tracer container 61, forward tracer contact 70assembly, conductor 72, fuze contact 74, conductor 75 and fuzeelectronic circuit 76. The return portion of the circuit may be providedby projectile 57 outer surface, unpainted driving band 56 and/orcartridge case 51, which overlaps with a portion of the driving band 56and is electrically connected to the head assembly holder 53. Whereasprojectile 57, driving band 56 and cartridge case 51 are often metallicin nature, thereby electrically-conductive, they may also be made ofother electrically-conductive materials. Where cartridge case 51 is of anon-electrically-conductive material, a dedicated conductor mayoptionally be provided linking projectile 57 with cartridge case base 52or reliance may be placed upon gun parts electrically connected throughthe driving band 56 to provide this electrical link.

FIG. 5 is a simplified schematic of the electromechanical circuitdescribed above and illustrated in FIG. 4, but also showing theassociated bridge wire 81 circuit for igniting propellant 55 (see FIG.6A for details). The bridge wire 81 is a resistance R which, uponreceiving the firing signal, will become sufficiently hot to ignite theprimer. As such, the bridge wire 81 constitutes the primer igniter. Thebridge wire 81 portion of the circuit is connected in the electroniccircuit so that diode D1 prevents the fuze-setting signal, havingappropriate polarity, from passing through bridge wire 81; and diode D2prevents the firing signal, of opposite polarity, from passing throughthe fuze electronic circuit to the fuze 63.

Thus diode D1 is electrically oriented to isolate bridge wire 81 fromthe electrical fuze-setting signal, thereby ensuring that this settingsignal for the programmable electronic circuit of fuze 76 does notignite bridge wire 81. And second diode D2 is electrically oriented toisolate fuze electronic circuit 76 during ignition of the propellant 55from the firing signal. Both diodes DI, D2 are electrically connected toreceive setting and firing signals through the electrode 80 of headassembly contact 67.

Although not absolutely necessary, diodes DI and D2 are present forredundant safety considerations. The difference in energy requirementsbetween the firing circuit and the fuze electronic circuit 76, theformer being at least 10 times greater than the latter, means that thesetting signal, even if allowed to pass through the bridge wire 81,would not normally ignite it. Nevertheless, the diodes DI and D2preclude the risk of a premature firing occurring, based on using afirst polarity for the setting signal and a second, opposite, polarityfor the electrical firing signal.

The head assembly contact 67 includes the head assembly holder 53 forcontaining head assembly components, as shown in FIGS. 6A, 6B and 6C.FIG. 6B is the same view as shown in FIG. 6A except that it is rotated90° along its longitudinal axis to illustrate the relative preferredpositioning of diodes DI and D2. This is further illustrated in the endview of head assembly contact 67 shown in FIG. 6C.

FIG. 6A details head assembly contact 67, which contains a firstelectrically-conductive cylindrical sleeve 88 fitted within the headassembly holder 53 for electrical connection to the firing pin 65contacting electrode 80. This first electrically-conductive cylindricalsleeve 88 is fitted into the head assembly holder 53 as a slidingengagement but separated electrically from the head assembly holder 53by first sleeve insulation means 87. An electrically non-conductiveadhesive may be employed to ensure that the firstelectrically-conductive cylindrical sleeve 88 is held in place withinthe head assembly holder 53.

A second electrically-conductive cylindrical sleeve 85 is fitted withinthe first electrically-conductive cylindrical sleeve 88, again by asliding engagement, optionally with electrically non-conductive adhesivepresent. This second electrically-conductive cylindrical sleeve 85 isfurther isolated electrically from the first electrically-conductivecylindrical sleeve 88 and the head assembly holder 53 by second sleeveinsulation means 88A.

Said head assembly contact 67 further contains the ignitioncup-sub-assembly 82 consisting of electrode 80 fitted within ignitioncup sub-assembly 82 as a sliding engagement but separated electricallyby ignition cup insulation means 86. Ignition cup sub-assembly 82further containing ignition charge 83 and bridge wire 81 is thenpreferably press-fitted into second electrically-conductive cylindricalsleeve 85 closing (or providing) electrical connection between electrode80, bridge wire 81, ignition cup sub-assembly 82 and secondelectrically-conductive cylindrical sleeve 85. Head assembly holder 53is electrically connected to second electrically-conductive cylindersleeve 85 with diode DI to complete the firing circuit.

Electrode 80 further makes electrical contact with the firstelectrically-conductive cylindrical sleeve 88. During assembly,electrode 80 is preferably press-fitted first through a circular hole inthe end of first electrically-conductive cylindrical sleeve 88 whilebeing electrically insulated from the head assembly holder 53 byinsulation means 93. Retainer 92 is then threaded to secondelectrically-conductive cylindrical sleeve 85 as an additional means tomaintain ignition cup sub-assembly 82 in place.

Said head assembly contact 67 further contains flash tube seat 90containing relay charge 84, fitted contiguous to retainer 92, andthreaded to second electrically-conductive cylindrical sleeve 85. Whenignition charge 83 is ignited, the relay charge 84 will be immediatelyignited also and release hot gases through the primer flash tube seat 90and into primer flash tube 54.

Diode D2 is electrically connected to the first electrically-conductivecylindrical sleeve 88 as part of the fuze-setting electromechanicalcircuit for carrying the electrical setting signal from the firing pin65 and head assembly contact 67 via electrode 80, said firstelectrically-conductive cylindrical sleeve 88, diode D2, connector 89and conductor 68 to fuze electronic circuit 76. Diode DI is electricallyconnected between the head assembly holder 53 and the second cylindricalsleeve 85 for carrying the electrical firing signal to the bridge wire81 for activation of ignition charge 83.

In FIG. 6B diode DI is shown as being oriented longitudinally, parallelto the axis of the cartridge. In fact, the outer periphery of the secondelectrically conductive, cylindrical sleeve 85 may be shortenedlongitudinally and provided with a seat or cutout along its outerperiphery and diode DI may be oriented to lie circumferentially alongthe outer surface of second electrically-conductive cylindrical sleeve85. In such case, diode DI may be nested within the cutout (see FIGS.6D, 6E and 6F).

In summary, FIGS. 6A, 6B and 6C illustrate how the head assembly contact67 contains:

-   -   head assembly holder 53;    -   electrode 80, upon which firing pin 65 bears;    -   insulation means 93;    -   ignition cup 82 for containing bridge wire 81, ignition charge        83 and ignition cup insulation means 86;    -   first electrically-conductive cylindrical sleeve 88;    -   second electrically-conductive cylindrical sleeve 85;    -   first sleeve insulation means 87 between head assembly holder 53        and first electrically-conductive cylindrical sleeve 88;    -   second sleeve insulation means 88A between first        electrically-conductive cylindrical sleeve 88 and second        electrically-conductive cylindrical sleeve 85;    -   connector 89 between diode D2 and conductor 68;    -   retainer 92, and    -   flash tube seat 90 containing relay charge 84.        Insulation means 86, 87, 88A and 93 may be made of either        plastic, a non-conductive anodized aluminum coating or any other        suitable insulating material for added strength. Once these        components have been assembled, flash tube seat 90 is fitted        within the second electrically-conductive cylindrical sleeve 85.        Then the rearward end of flash tube 54 is also fitted into        second electrically-conductive cylindrical sleeve 85.

Although connector 89 may be of any suitable design, the press-fitvariety is preferred because of its easier installation. A press fitconnector may also be used to effect the connection between diode DI andhead assembly holder 53 and between diode D1 at the secondelectrically-conductive cylindrical sleeve 85.

As can be followed in FIG. 6A, the fuze-setting signal enters thecartridge 50 through electrode 80, passes through firstelectrically-conductive cylindrical sleeve 88 to diode D2 and thenthrough connector 89 to conductor 68. Diode D2, which is connected tofirst cylindrical sleeve 88, is shown in FIG. 6A as overlying the secondelectrically-conductive cylindrical sleeve 85. Diode D2, however, couldbe located anywhere in the electromechanical circuit (e.g., anywherealong conductors 68 or 72, or embedded in fuze 63).

Firing signal current passes along a firing path that includes electrode80, bridge wire 81, ignition cup sub-assembly 82, secondelectrically-conductive cylindrical sleeve 85, diode D1 and headassembly holder 53 (FIG. 6B).

FIG. 7A illustrates rear tracer contact 69, which comprises primer flashtube 54, primer flash tube end closure 100, non-conducting forward endretainer 101 with longitudinal slot 102 containing conductor 68,non-conducting (e.g., cardboard) guide tube/funnel 104, non-conductingplug 105, electrically-conductive plug 106 with connector post 107,electrically-conductive spring-loaded connector 110,electrically-conductive disk 111, and tracer unit 61A withelectrically-conductive tracer container 61 and tracer compound 62. Theincoming setting signal from head assembly contact 67 is carried byconductor 68 and enters rear tracer contact 69 at connector post 107.Thereafter it travels through electrically-conductive plug 106,electrically-conductive spring-loaded connector 110,electrically-conductive disk 111, electrically-conductive tracercontainer 61 and onwards to forward tracer contact 70.

In FIG. 7A, the setting signal is insulated from metallic primer flashtube 54 and metallic primer flash tube end closure 100 by non-conductiveforward end retainer 101 and non-conductive (typically plastic) plug105. Electrically-conductive spring-loaded connector 110 is compressedto ensure a positive contact with electrically-conductive plug 106 atone end and with electrically-conductive disk 111 at the other end. Thesetting signal is constrained to pass through electrically-conductivespring-loaded connector 110 by non-conducting forward end retainer 101.Electrically-conductive disk 111 is included to preventelectrically-conductive spring-loaded connector 110 from damaging thethin end wall of electrically-conductive tracer container 61. The sidewall of said tracer container 61 is much thicker in most instances.

FIG. 7B illustrates, prior to insertion of tracer unit 61A, tracer seat112, which is formed by non-conducting guide tube/funnel 104, andelectrically-conductive disk 111 (adjacent to and in contact withelectrically-conductive spring-loaded connector 110). As explained inmore detail at FIG. 10 below, tracer unit 61A is inserted into tracerseat 112 during final assembly of cartridge 50.

FIG. 8A illustrates forward tracer contact 70, which comprises tracerunit 61 A with electrically-conductive tracer container 61 containingtracer compound 62, tracer base 120, non-conducting guide tube/funnel104, non-conducting high-pressure washer 121, non-conducting nut 122,electrically-conductive spring-loaded connector 123 located in conduit71, threaded non-conducting sleeve 124, insulatedelectrically-conductive high-pressure seal 125, connector post 126, andconductor 72. Threaded non-conductive sleeve 124 holdselectrically-conductive spring-loaded connector 123 within its hollowcore and ensures that insulated electrically-conductive high-pressureseal 125 is firmly seated in place by being screwed into projectile base58 of projectile 57. The insulation for electrically-conductivehigh-pressure seal 125 may be provided, for example, by a non-conductiveconical outer surface 127.

High-pressure seal 125 is shown in FIG. 8B as being conical in shape,but it may also be spherical, cylindrical or any other suitable shapethat responds to pressure on one side by ensuring the effectiveness ofthe seal with the sidewalls of the seating orifice formed in the base ofthe projectile. Although preferably made of metal, seal 125 may also befabricated from any other suitable material that meets its designrequirements (e.g., a ceramic or reinforced plastic material withprovision to provide electrical conduction).

The incoming setting signal from rear tracer contact 69 travels alongelectrically-conductive tracer container 61 to electrically-conductivetracer base 120, 30 then through electrically-conductive spring-loadedconnector 123 and high-pressure seal 125 to connector post 126 andconductor 72, which leads to fuze contact 74.

Electrically-conductive high-pressure seal 125 is illustrated in FIG. 8Bin its preferred conical embodiment with its outer surface 127 insulatedby, for example, anodizing of the aluminum from which it may bemanufactured. Thus, the fuze setting signal in FIG. 8A is insulated fromprojectile base 58 of projectile 57 by non-conducting washer 121,non-conducting nut 122, threaded non-conductive sleeve 124 and theinsulated outer surface 127 of high-pressure seal 125. Non-conductivehigh-pressure washer 121 and non-conductive. nut 122 may be made, forexample, from. anodized aluminum; other materials that provide similarperformance may also be used. These high-pressure seals are required toisolate high explosive 60 from the hot propellant gases produced by theburning of propellant 55 contained in cartridge case 51 after the firingof cartridge 50 (see FIG. 4). Non-conducting guide tube/funnel 104(preferably cardboard or some other non-electrostatic material) plays nodirect role in the electromechanical circuit described herein for thesetting signal; rather, it is present to prevent crushing of propellant55 when projectile 57 is inserted into cartridge case 51 during assemblyof cartridge 50 as well as to guide tracer unit 61A into place (see FIG.10).

FIG. 8C is an alternative design to that shown in FIG. 8A. It addsinsulated (as by a non-conductive coating) conical,electrically-conductive, high-pressure seal 130 as a backup tohigh-pressure seal 125 and high-pressure washer 121 to ensure againstthe possibility of hot propellant gases reaching high explosive 60 andcausing premature detonation. In this configuration, threadednon-conducting tube 131 is added to hold insulatedelectrically-conductive high-pressure seal 130 in place. Thus, thesetting signal passes through electrically-conductive spring-loadedconnector 132, insulated electrically-conductive high-pressure seal 130,electrically-conductive spring-loaded connector 133 and insulatedelectrically-conductive high-pressure seal 125 to reach connector post126 and conductor 72.

FIG. 9A illustrates fuze contact 74, which comprises conduit 73 throughwhich conductor 72 passes to meet and join with electrically-conductivespring-loaded connector 140, which is also attached to connector post141 at the forward end of projectile body 57A. Connector post 141 ofprojectile body 57A mates with annular ring conductor (or connector) 142having a centre point and located in annular groove 143 on the fuze base63A of programmable multifunctional electronic fuze 63 (FIG. 9B).Annular ring conductor 142 is insulated from fuze 63 by insulatingcircular insert 145, which is seated in annular groove 143 (FIG. 9C).Insulating circular insert 145 may be polymeric in nature, or any othersuitable insulating material. Conductor 75 completes theelectromechanical circuit linking fire control system 64 with fuzeelectronic circuit 76 of fuze 63.

Annular ring connector 142 consists of a gold (or other suitableconductive material) plated ring seated in insulating circular insert145 fitted within full 360° circumference of annular groove 143, therebyensuring a positive electrical connection at point of contact 74Aregardless of the orientation of fuze 63 with respect to projectile body57A when it is screwed into booster cavity 144 of projectile body 57Athrough a rotational coupling. Any rotational coupling having a centralrotational axis aligned with the projectile and passing through thecentre point of annular ring conductor 142 can be used to attach thefuze 63 to the projectile.

The described embodiment has connector post 141 on projectile body 57Aand the annular connector 142 on fuze 63. Alternately, annular connector142 and connector post 141 with electrically-conductive spring-loadedconnector 140 may be reversed with the former electrically-conductive byprojectile body 57A and the latter carried by fuze 63.

FIG. 10 illustrates the final cartridge assembly procedure. Casepreassembly 150, comprises principally cartridge case 51 loaded withpropellant 55, primer flash tube 54, head assembly contact 67, conductor68, rear tracer contact 69 with spring loaded connector 110, andnon-conducting guide tube/funnel 104. Projectile preassembly 151comprises principally projectile 57 with projectile body 57A loaded withhigh explosive 60, forward tracer contact 70, conductor 72, point ofcontact 74A, fuze 63, and tracer unit 61A with electrically-conductivetracer container 61. When projectile preassembly 151 is lowered intocase preassembly 150, tracer unit 61A is guided into position bynon-conducting guide tube/funnel 104 until contact is made between theend of tracer container 61 of projectile preassembly 151 andspring-loaded connector 110 of case preassembly 150. The case/projectileinterface for the fuze setting circuit is ensured by a positivecompression of spring-loaded connector 110 by electrically-conductivetracer container 61, thereby connecting the two parts of the fuzesetting-signal circuit contained respectively in case preassembly 150and projectile preassembly 151. This “plug-in” operation providessimultaneous mechanical and electrical coupling at the case/projectileinterface and, by its very simplicity, is an important contributor toboth safety and reliability.

The use of the electrically-conductive tracer container 61 as part ofthe fuze-setting circuit allows the projectile to be mountedmechanically on the cartridge case 51 without any extra steps beingnecessary to effect an electrical connection. This is important because,when these components are mated, the cartridge case 51 is filled withpropellant 55 and the projectile contains high explosive 60. In suchconditions, assembly should be as simple as possible. For similarreasons, the fuze 63 portion, upon assembly, also effects simultaneousmechanical and electrical connections to the projectile when it isscrewed into place.

In tests the electromechanical circuit described herein has demonstratedthat it contributes appreciably to economical manufacturing techniqueswhile yielding highly reliable and safe transmission of signals from thefire control system to the programmable fuze in a 105 mm gun such as inthe Leopard tank.

As referenced previously, although the invention is described in respectto setting a fuze, the invention could also be used to activate atrigger for programming a camera, activating a chemical sensor,turning-on a target designator-illuminator or actuating other similartypes of payload. Accordingly, when reference is made to “fuze” in thedisclosure and in the claims, this word is intended to include any sortof payload electronic device. And similarly, the explosive is describedas simply an example of a payload. Accordingly, when a reference is madeto “explosive” in the disclosure and in the claims, this word isintended to include any sort of payload.

The features of the invention as described therefore successfullyaddress the object of a rendering assembly of the final shell as simpleas possible.

CONCLUSION

The foregoing constitutes a description of specific embodiments showinghow the invention may be applied and put into use. These embodiments areonly exemplary. The invention in its broadest and more specific aspectsis further described and defined in the claims which now follow.

These claims, and the language used therein, are to be understood interms of the variants of the invention which has been described. Theyare not to be restricted to such variants, but are to be read ascovering the full scope of the invention as is implicit within theinvention and the disclosure that has been provided herein.

1-32. (canceled)
 33. A forward contact for use in an electromechanicalelectronics-setting circuit present within a cartridge; said cartridgecomprising a case with a head assembly and a load carrying projectilefitted to said case, said projectile having programmable electronicsmounted therein at its forward end, said electromechanicalelectronics-setting circuit designed for transmitting an electricalsetting signal originating from an external fire control system throughthe head assembly to said programmable electronics; said projectilehaving a base with a conduit penetrating there-through that communicateswith the payload-containing interior of the projectile through ahigh-pressure seat; wherein said forward contact comprises: a) a unitwith an electrically-conductive container; b) a base; and c) aconductive, spring-loaded high-pressure sealing connector insulated fromsaid case and slidingly seated at least partially within saidhigh-pressure seat to effect a high-pressure seal of said conduit andprevent hot propellant gases arising upon firing of the cartridge fromreaching the payload contained in the projectile while maintaining anelectrically conductive path into the interior of the projectile that isinsulated from said case; with said electromechanical circuit having apath originating from said external firing control system, to anelectrode present in said head assembly, to a first conductor, to saidforward contact, to a second conductor, to a fuze contact within saidprojectile, to a third conductor, to said programmable electronics,returning via a surface of said cartridge to ground.
 34. The forwardcontact of claim 33, wherein said conductive, spring-loadedhigh-pressure sealing connector comprises an electrically-conductivespring loaded connector and an insulated electrically-conductivehigh-pressure seal, with the insulated electrically-conductivehigh-pressure seal placed between the electrically-conductive springloaded connector and the payload.
 35. The forward contact of claim 34,wherein the insulated electrically-conductive high-pressure seal isconical, spherical, cylindrical or other suitable shape.
 36. The forwardcontact of claim 35, wherein said conductive, spring-loadedhigh-pressure sealing connector comprises a first and secondelectrically-conductive spring loaded connector; and a first and secondinsulated electrically-conductive high-pressure seal, such that theelectromechanical circuit path includes a segment from the firstconductor, to the first spring-loaded high-pressure connector, to thefirst insulated electrically-conductive high-pressure seal, to thesecond spring-loaded high-pressure connector, to the second insulatedelectrically-conductive high-pressure seal, and to the second conductor.37. The forward contact of claim 36, wherein the first and secondinsulated electrically-conductive high-pressure seals are each conical,spherical, cylindrical or other suitable shape.
 38. The forward contactof claim 33, wherein the electrically-conductive container comprises atracer.
 39. The forward contact of claim 33, wherein theelectrically-conductive container comprises a base burner.
 40. Theforward contact of claim 33, wherein the electrically-conductivecontainer comprises a rocket motor system.